# File lib/facter/core/execution/posix.rb, line 12
  def which(bin)
    if absolute_path?(bin)
      return bin if File.executable?(bin) and File.file?(bin)
    else
      search_paths.each do |dir|
        dest = File.join(dir, bin)
        return dest if File.executable?(dest) and File.file?(dest)
      end
    end
    nil
  end